[Effect of the correlation between gut microbiota and folic acid in first-episode schizophrenia]

Objective: To explore the effects of gut microbiota and the serum level of folicacid on psychiatric symptoms in first-episode, drug-free schizophrenic (SCZ) patients. Methods: A total of 100 first-episode, drug-free SCZ patients (SCZ group) from the First Affiliated Hospital of Zhengzhou University and 90 demographically matched healthy individuals (healthy control group) were enrolled. The serum level of folic acid was measured by the electrochemical luminescence method.Positive and Negative Syndrome Scale (PANSS) was used to assess the psychiatric symptoms and Matrics Consensus Cognitive Battery (MCCB) was used to evaluate cognitive function. Bacterial DNA was extracted from the fecal samples for high-through put sequencing of the 16S rRNA.The effects of gut microbiota and folic acid on the psychiatric symptoms and cognitive function in SCZ patients were explored. Results: A total of 41 males and 59 females, with an age of (22.6±8.2) years were included in the patient group, and 32 males and 58 females with an age of (23.0±3.0) years were included in the healthy control group. The fasting folic acid level inserum of the SCZ group was lower than that of healthy control group [6.92(4.98, 8.49) μg/L vs 8.93(7.13, 13.37) μg/L,P<0.001]. The relative abundance of genus Bifidobacterium[0.005(0.003, 0.013) vs 0.014(0.004, 0.031)] and genus Bacteroides[0.015(0.001, 0.091) vs 0.083(0.029, 0.193)]was lower in the SCZ group than that of the healthy control group (both P<0.001). In comparison with the healthy control group, scores of cognitive function in the seven domains were significantly lower in the SCZ group (all P<0.05). In the patient group, the serum level of folic acid was negatively related to the negative symptom score(r=-0.378, P<0.001), but had a positive correlation with the score of speed of processing (r=0.310, P=0.011).In the SCZ group, the relative abundance of the genus Bifidobacterium was positively correlated with the serum level of folic acid (r=0.374,P<0.001) and the score of speed of processing(r=0.330,P=0.003) respectively, but was negatively correlated with the general psychopathology score (r=-0.326, P=0.001). The results of multiple linear regression analysis showed that the interaction term between folic acid and genus Bifidobacteriumin in SCZ patients were correlated with the general psychopathology score, with a regression coefficient of -29.240 (F=8.655, P=0.007). There was no statistical correlation between the aforementioned interaction term and cognitive function (both P>0.05). Conclusion: In first-episode, drug-free SCZ patients, there were decreases in the serum folic acid level and the relative abundance of genus Bifidobacterium, which were related to the psychiatric symptoms, suggesting that these two substances can be used as potential objective indicators for evaluating psychiatric symptoms.